LOS ANGELES (Embargoed Until April 22, 1999) - A Cedars-Sinai Medical Center neurologist and researcher into genetic neurological disorders will provide details of recent findings related to spinocerebellar ataxia type 2 (SCA2) and describe advances in determining the chromosomal location of a new ataxia-related gene at the upcoming annual meeting of the American Academy of Neurology.
Stefan-M. Pulst, M.D., Carmen and Louis Warschaw Chair in Neuruology at Cedars-Sinai, is scheduled to present two educational and five scientific sessions during the AAN's convention to be held April 17 through 24 in Toronto.
In a presentation Thursday afternoon, Dr. Pulst will announce the recent discovery of a protein that is involved in causing human brain tumors. Identified by a member of Dr. Pulst's team, this protein binds to a protein that suppresses tumor growth. The presence of the tumor-suppressing protein appears to be required for the tumor-causing protein to function. This discovery will open new avenues for the treatment of brain tumors.
The subject of several of the week's earlier sessions is ataxia. Characterized by unsteadiness and an inability to coordinate muscle movements, this disorder may result from a variety of causes, both hereditary and acquired. More than 150,000 Americans suffer from ataxia.
A subset of ataxias, autosomal dominant cerebellar ataxias (ADCAs), have genetic origins and impact the cerebellum of the brain, which is involved in the coordination of muscular movements. Because of the inability to control muscle actions, patients with ADCAs typically exhibit rapid and exaggerated movement, speech problems, and tremor when attempting voluntary movement.
To date, five spinocerebellar ataxia (SCA) genes have been identified: SCA 1, 2, 3, 6, and 7. The chromosomal locations of SCA 4 and 5 have been pinpointed. At the AAN meetings, Dr. Pulst's team will describe the mapping of a new gene, SCA10, to a region on chromosome 22. SCA10 causes loss of gait and limb control, speech impairment, involuntary movement of the eyes, and epileptic seizures.
Two of Dr. Pulst's scientific presentations will be devoted to providing information from new studies on SCA2. Dr. Pulst served as one of the lead scientists in the 1996 discovery of SCA2, and he and his colleagues continue to analyze its origins, characteristics, development and impact.
For example, in studies of human brain sections and transgenic mice which express the human SCA2 mutation, they have identified basic mechanisms within SCA2 cells that differ from those in the other genes associated with neurodegenerative diseases.
Before the discovery of SCA2 and the other altered genes, clinical histories were the only way to diagnose ADCAs. Now, accurate diagnosis available through genetic testing provides vital information for predicting the course of disease and the likelihood of transmission from generation to generation.
DR. PULST'S PRESENTATION TOPICS AND TIMES:
Sunday, April 18, 3:15 p.m. "SCA2: Absence of Intranuclear Aggregates and Animal Model." A description of the ways in which SCA2 differs from similar genes.
Monday, April 19, 9 a.m. "Molecular Genetic Testing for Neurologic Diseases," and 9:45 a.m. "Genetic Testing for Patients With Ataxia." Dr. Pulst will present these two educational sessions during a half-day course he is chairing.
Tuesday, April 20, 3 p.m. "Evidence for a Second Locus for Rippling Muscle Disease." Rippling muscle disease (RMD) is an inherited disorder of skeletal muscle that causes muscle cramps, pain and stiffness, particularly during exercise. One locus (location on a chromosome) responsible for RMD has been previously mapped. Dr. Pulst will identify a new one.
Wednesday, April 21, 9:45 a.m. "The SCA2 Gene Product, Ataxin-2, Interacts with a Novel Protein, A2BP, a Member of a RNA Binding Gene Family." SCA2 is a member of a group known as "triplet repeat diseases" or "CAG repeat diseases." The gene, found on chromosome 12, normally contains a string of 15 to 29 "repeats" of a sequence in the genetic code: cytosine, adenine and guanine (CAG). In the case of SCA2, however, the gene contains from 36 to 59 CAG repeats. Other CAG mutations include SCA1; SCA3 (Machado-Joseph disease); SCA6; SCA7; Huntington's disease; spinobulbar muscular atrophy (SBMA or Kennedy's disease); and dentatorubral-pallidoluysian atrophy (DRPLA). By identifying and understanding the intricate, intracellular mechanisms by which SCA2 functions, researchers hope to eventually find treatments and cures not only for SCA2 but for these other neurogenerative diseases as well.
Wednesday, April 21, 10:15 a.m. "Mapping of a New Autosomal Dominant Spinocerebellar Ataxia (SCA10) to a 15 cM Region on Chromosome 22."
Thursday, April 22, 2:45 p.m. "The Neurofibromatosis 2 (NF2) Interacting Protein SBP3 Is Not Expressed in Vestibular Schwannomas." Several types of brain tumors may be caused by a mutation in the neurofibromatosis 2 (NF2) tumor suppressor gene. A protein within NF2, schwannomin, appears to act as a tumor suppressor but little else is known about this substance. This study was designed to further scientists' understanding of schwannomin by identifying and analyzing certain proteins (particularly schwannomin-binding protein, or SBP3) with which it interacts. According to the results, SBP3 appears to be an important protein in the development of the NF2 tumor suppressor gene, and the expression of schwannomin is necessary for the stability and proper localization of SBP3.
To arrange a media interview, please call 1-800-396-1002 (Please do not publish this number in stories).
EMBARGO NOTE: Although the overall embargo date is April 22, certain of this information may be released earlier depending on presentation dates and times. To ascertain early release dates, please call 1-800-396-1002.